Power shortage drives many nations to develop various substitute energies, especially solar energy. Solar energy is easy to access and pollution-free. Besides, solar cells are noiseless and have a long service life. Therefore, much money has been invested in research of solar energy. Recently, many technologies have been developed to improve the utilization efficiency of incident light and enhance the photoelectric conversion efficiency, such as changing the interface material, roughening the surface or arranging an anti-reflection layer.
In addition to promoting the photoelectric conversion efficiency, reducing the fabrication cost to increase the economic profit is also a focus subject of solar cell development. The cost of solar cells can be reduced via decreasing the material cost or improving the fabrication process. The electric-conduction layer on the light-incident surface of a solar cell must be made of a material featuring transparency and electric conductibility, such as ITO (Indium Tin Oxide), which is relatively expensive. Further, the fabrication process of solar cells requires precision CVD (Chemical Vapor Deposition) equipment, which makes the fabrication cost hard to reduce.